Alarms within land vehicles that signal burglary or unauthorized use are well known. When in a state to detect intrusion or unauthorized use, such alarms are typically responsive to movement, such as a door being opened, or certain operation, such as the engine being started. Such alarms typically enable a sound generating device, or a light producing device, or both. The response of some alarms is to activate a radio transmitter located within the vehicle.
U.S. Pat. No. 5,463,372 issued Oct. 31, 1995, to Mawyer, Sr., describes an anti-theft alarm with partial disablement, followed by complete shutdown of the engine of a vehicle in response to the output of a radio receiver, located within the vehicle, having been wirelessly activated by a radio signal from a remotely located transmitter. Upon occurrence of an alarm condition, an output from the anti-theft alarm of Mawyer, Sr., causes erratic operation of the ignition, thereby greatly reducing engine power but providing sufficient power so that it would be possible to get the vehicle out of traffic and to the side of a road. After a pre-determined period of time has elapsed from occurrence of the alarm condition, the anti-theft alarm completely shuts down the engine by causing the ignition to cease operating. Disadvantageously, the anti-theft alarm of Mawyer, Sr., has no provision for altering its output in response to the speed of the engine. That is, the anti-theft device of Mawyer, Sr., disables the engine at the same rate regardless of the speed of the engine. Also, if the engine is running very slowly when the radio signal is received, the anti-theft alarm of Mawyer, Sr., has no provision for immediately shutting down the engine.
Thus, what is needed is an alarm device, activated by a selective call radio signal that varies the rate disablement of a land vehicle in response to the speed of the engine of the land vehicle.